augroup markdown
  autocmd!
  autocmd BufNewFile,BufRead *.Rmd,*.rmd set ft=rmd
  autocmd BufNewFile,BufRead *.md,*.markdown set ft=markdown
  autocmd BufNewFile,BufRead *.md,*.markdown set syntax=rmd
augroup end

augroup netrw
  autocmd!
  autocmd FileType netrw setl bufhidden=wipe
augroup end